This invention relates to hammocks, particularly one in which an occupant is supported by material suspended between at least two points. An occupant suspended above the ground in a hammock may rest from a few hours for daytime napping up to a full night sleep in places where the hammock is a substitute for a bed, such as a board ship or in some countries.
Hammocks in general have been used for thousands of years, however most recent improvements appear in the last 100 years.
Prior art patents show different concepts and inventions related to increase level surface, spreader bar improvements, variable tensioning of fabrics, specific fabric shapes and asymmetric position of fabric and spreader bars. Graham's U.S. Pat. No. 645,805, Potter's U.S. Pat. No. 717,119, Hall's U.S. Pat. No. 4,001,902, Fueslein's U.S. Pat. No. 4,021,868, Scott's U.S. Pat. No. 6,347,638, Eriksen's U.S. Pat. No. 6,701,549, Hennessey's U.S. Pat. No. 6,865,757 and Helsdon's U.S. Pat. No. 7,020,915 each show improvements to hammocks. These patents show various ways to achieve some improvement of comfort as less curvature lengthwise for the occupant usually at the detriment of the lateral flatness of the hammock. Some others are keeping the lateral flatness to the detriment of a multi-steep flatness lengthwise.
Most hammock materials used today have a strong longitudinal strength with low elongation of around 2 to 5 percent in that direction which allows a person to lie in the hammock and be well supported, especially if a pre-tension of 20 to 100 lbs is made upon installing the hammock.
Many hammocks are so concave from side to side that any field of vision horizontally is gone and the occupant is constrained to resist a high level of side to side pressure.
A final and important drawback to most patents using only a two-ring support system, is when a higher tension is applied on the rings in order to improve the level lengthwise, a similar decrease of stability is brought about making it nearly impossible to stay on the hammock.